Romestead potion problems are solved through the cauldron, but you cannot craft base health potions from scratch; you have to buy or find the starter potions first, then upgrade them with materials. Here’s how:
How to make potions
Step 1: Unlock the cauldron
Progress far enough to unlock the blacksmith.

Then have the blacksmith craft a cauldron for 4 copper ingots. The copper ingots must be smelted in the furnace with a log, so do not look for a blacksmith recipe for the ingots themselves.

Step 2: Stock empty pots
Get empty pots before you try to brew anything, because the system depends on them. You can craft five at the pottery using 1 tub, 1 barrel, and 1 bucket of clay, or buy them from the market once it is unlocked.

Step 3: Buy or loot starter potions
You cannot craft basic health potions from nothing yet, so get the first copy from the market trader or from dungeon loot. The starter option is the minor health potion, while stronger tiers appear later through upgrades.

Step 4: Upgrade the potion tier
Combine the starter potion with the correct resource to improve it. Go with minor health potion + bush crab meat for the first upgrade, then repeat the idea with more materials to reach minor health potion plus plus.

Step 5: Use the right biome materials
For stronger tiers, use biome-specific ingredients instead of guessing. Aloe vera from the desert upgrades the normal health potion, while honey is used for the larger major potion tier.

Step 6: Craft utility potions
The cauldron also supports non-healing effects such as poison potion materials, fire-resistance style healing salve materials, and an antidote-style potion, but some of these are not very efficient compared with healing.
Respawn boss fights
Step 1: Keep the boss drop
After beating a boss, do not donate or sell the unique drop if you want to farm it again. For the first boss, the key item is the eye; for the cyclops, it is the tooth needed for the effigy recipe.
Step 2: Craft the effigy
Use the saved boss drop to craft the matching effigy.

That effigy is what lets you set up repeat boss farming, instead of treating the kill as a one-time progression wall.

Step 3: Wait for the boss to return
Leave the area alone for a few in-game days so the boss respawns naturally. Once it is back, you can fight it again and collect more drops for another effigy or for gear farming.

Step 4: Farm early-game gear
Use the repeat fight to farm the early armor and weapon upgrades, because the gear falls off in value quickly as you advance. That makes boss reruns most useful when you want a stronger early-game setup.
Critical mistakes to avoid
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Do not assume the blacksmith makes copper ingots; the ingots are smelted in the furnace first.
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Do not expect to craft basic potions from scratch, because the system currently requires a bought or looted starter potion.
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Do not spend boss eyes or teeth if you want to craft effigies later.
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Do not place the cauldron carelessly, because it is hard to move after placement.
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Do not rely on food alone in boss fights if you need quick healing, because potion use is faster in emergencies.
Best potion route
The most efficient early route is this – unlock blacksmith, smelt copper, craft cauldron, unlock the market, buy a starter health potion, then upgrade that potion with the correct biome resource. For boss farming, the best route is: save the boss drop, craft the effigy, wait for the respawn, and repeat.
Romestead potion crafting is clearer once you know the loop: buy or loot the first potion, upgrade it with the right materials, and use boss drops to craft effigies for repeat fights.